Apnoea literally means ‘no breath’ or ‘stopping breathing’, so sleep apnoea is repeated disruption of normal breathing while you sleep.
Many people have sleep apnoea, and we suspect many more may have it and not even know it. In fact, sleep apnoea affects just under 20% of women and just over 30% of men, so it’s more common than you might think. If you think you might have sleep apnoea, it’s important to get it assessed and get on top of it.
There are three types of Sleep Apnoea.
Obstructive sleep apnoea (OSA) is the most common type of sleep apnoea. It occurs when the soft tissue in the back of the throat relaxes during sleep and block the upper airway. This often causes you to snore loudly. OSA is common and affects 38% of the general adult population. Who does it tend to occur in?
In OSA, collapse of the upper airway can be either complete, leading to cessation of airflow (apnoea), or partial, leading to a reduction in airflow (hypopnoea). Partial collapse is more common than complete.
Central sleep apnoea (CSA) is a much less common type of sleep apnoea that involves the central nervous system. This occurs when the brain fails to signal the muscles that control the airway and breathing. In some cases, the airway is actually open but air stops flowing to the lungs because no effort is made to breathe. This is because the communication between the brain and the body has been affected so the automatic action of breathing stops. People with CSA don’t often snore, so the condition sometimes goes unnoticed.
CSA is characterised by repetitive episodes of shallow or absent breathing, resulting from temporary loss of breathing effort. That is, breathing ceases because the thoracic and abdominal muscles lose their instruction from the brain to continue moving air to and from the lungs.
Complex or mixed sleep apnoea is a combination of obstructive sleep apnoea and central sleep apnoea.
This is a mixture of both obstructive sleep apnea OSA (where there is a blockage or obstruction in the upper airway) and CSA (where no effort is made to breathe). Complex sleep apnoea is the term used to describe a form of sleep disordered breathing in which repeated central apnoea’s (>5/hour) persist or emerge when obstructive events are extinguished with positive airway pressure (PAP) and for which there is not a clear cause for the central apnoea.
The Apnoea Hypopnoea index (AHI) reflects the severity of sleep disordered breathing and it measures the number of breathing disturbances per hour of sleep
– Mild to moderate is 5-15 events per hour, minimally symptomatic
– Moderate to severe is >15 events per hour, more commonly symptomatic and associated with other adverse outcomes such as cardiovascular and cerebrovascular disease, cognitive decline, MVAs and depression.